196 



LEON J, COLE. 



Proportionate Measurements of Endeis spinosus from Different Localities. 



Localities. 



Naples 



England 



Norway 



Vineyard Sound, ad. 

 " " juv. 



Tortugas, ad 



juv 



Of even more interest than the mere fact of the occurrence 

 of Endeis spinosus on the American coast is its peculiar pelagic 

 habitat on this side of the Atlantic. So far as I am aware, .a 

 pelagic habit among the Pycnogonida has not heretofore been 

 reported, either for this species, which in Europe has been re- 

 corded as dredged from shallow depths, or any other. In a 

 previous paper (Cole, 1901, p. 197) I have called attention to 

 the fact that Pallene brevirostris, a very slender pycnogonid 

 which occurs at Woods Hole, swims actively if by chance it 

 becomes free in the water; but ordinarily it lives among the 

 hydroids and algse growing attached in shallow water. Curiously 

 enough the specimens of Endeis from the Tortugas sent me by 

 Dr. Mayer are all recorded as having been obtained from the 

 "surface" or in the "tow." And in addition to these he has 

 also sent me several specimens of Pallene and Nymphon (species 

 as yet undetermined) which were obtained in the same manner. 

 While enjoying the privileges of the Carnegie Laboratory at 



(linear dimensions) which can be measured with ease and accuracy, it would seem 

 that these animals present exceptionally favorable material for a statistical study 

 of differentiation and correlation of these appendages. What observations and 

 measurements I have made would seem to indicate, for example, that the ratio of 

 the length of the legs to the body, and the correlation between the legs themselves, 

 varies with the age of the animal, and that there is a positive correlation between 

 the age of the individual and the position of the legs from behind forward. In 

 other words, the posterior pairs of legs present more juvenile characters than the 

 anterior ones. Such a study could be made profitably only on a species which 

 could be obtained in abundance at all stages of growth. The species under con- 

 sideration would be excellent for such a study, and Anoplodactylus lentus is another 

 that may be obtained abundantly at Woods Hole. Whatever else of general in- 

 terest might be learned, the results would be of the greatest value to the systematist 

 in this group, who has usually to deal with a small number of specimens taken at 

 scattered localities. 



